[Ol' Dan Tucker]

There are three possiblities:

There's a fourth possibility.

Beatty was given an envelope that contained a card that said, 'Emma Stone', and underneath, 'La La Land'.

Beatty was confused and handed the card to Dunaway, who interpreted it to mean La La Land won Best Picture.

IOW, someone at PWC put a duplicate of the Best Actress card inside the envelope meant to be read when awarding Best Picture.

Or, at least that's what I saw when I was watching the show.

What did you see?

[SkyPilot]

I didn't watch it, but I have read the accounts from this morning stating your 4th option as the factual basis.

I had previously read that Emma Stone said that she was given her Best Actress card as a memento from DiCaprio, and had it on her person when the Best Picture category was announced. So the story refuted that possibility, until it came to light this morning that Price Waterhouse has said they gave a duplicate envelope to Beatty and Dunaway.

It that is what occurred, then that's what happened.

But none of that will disabuse me of the notion that Moonlight winning was because of Hollywood affirmative action and a response to the black protests that the Oscar winners were "too white" last year.